DESCRIPTION (adapted from the investigator's description): The principal goal of this study is to understand the regulatory, physiological and evolutionary aspects of the cellular translational apparatus, especially rRNA. The focus will be on three major topics: reconstitution of the rRNA antitermination system, control of rRNA synthesis, and studies of strains with multiply inactivated rRNA operons. The objectives of this proposal are: 1. Reconstitution of the rRNA antitermination system, with the goal of identifying the factors and mechanisms involved. Biochemical studies will be used to complete the characterization of the rRNA antitermination system, then examine the mechanistic interactions of the required factors with each other and with RNA polymerase. 2. Mechanism of action of NusB in rRNA antitermination. The goal is to thoroughly characterize the interactions of one of the factors known to be essential for rRNA antitermination with the other components of the system. Such a study will lead to an understanding of precisely how the building blocks are put together for modifying RNAP so that it can elongate transcripts faster, read through terminators, and perhaps aid in the assembly of functional ribosomes. 3. Electron microscopic examination of rrn operon transcription under varied physiological and genetic conditions. These studies will provide information about rRNA transcription at the level of individual genes. Variations in regulatory conditions and altered operon composition will give precise information about features such as the mechanism of transcription of rrn operons and rRNA processing. 4. Strains with multiply inactivated operons. Questions previously difficult to answer because of the redundancy of rRNA gene copies can be addressed using these rRNA deletion strains. A variety of fundamental questions will be addressed concerning cell physiology and ribosome structure, function, synthesis and evolution. The importance of these studies lies in their ability to address fundamental questions about the cellular translation machinery that will apply to all living systems.